Inflammation causing spinal and joint pain can be difficult to treat. Increasing degrees of inflammation and force applied to joints result in joint injury. Abnormal joint anatomy can be a hallmark of aging, but joint injury can be also a result of trauma, such as chondral lesions often seen in athletes. While joint injury resulting from trauma can be typically associated with acute inflammation, aberrant joint anatomy resulting from aging (e.g., osteoarthritis) can be a chronic condition. Physicians currently do not have a system or method available to differentiate between acute injury due to trauma and age related joint deteriorations.
Presently, it can be difficult to determine the appropriate course of treatment for a given patient since it can be frequently unclear whether the particular condition the patient suffers from may be acute or chronic or if pathology in the joint is the cause of the pain.
Spinal-related pain can be typically classified as discogenic, facetogenic or radiculopathic pain. The manifestation of radiculopathic pain has traditionally been attributed to various physical and/or mechanical abnormalities, such as compression or mechanical irritation of the nerve root related to conditions such as disc herniation, stenosis, spondylolisthesis, sciatica, piriformis syndrome, obturator syndrome, cystic lesions (e.g., ganglion and synovial), tumors, and other pathology, such as chemically mediated causes.
Numerous studies have attempted to elucidate the pathophysiology of spinal-related pain, and several molecular pathways have been implicated tentatively. However, no clear causal pathway leading from injury or degeneration to the painful state has been confirmed. Molecular markers can be linked to clinical symptoms, and serve as potential targets for the development of diagnostics and therapeutic tools. Although some studies have provided evidence that the epidural space can be affected by an intervertebral disc herniation, none has measured concentrations of biomolecules in the epidural space in an attempt to detect the differences between affected and non-affected persons.
Tendons, which connect muscle to bone, and ligaments, which connect bones to other bones, are both composed of bands of fibrous connective tissue. The cells of the fibrous connective tissue are mostly made up of fibroblasts the irregular, branching cells that secrete strong fibrous proteins (such as collagens, reticular and elastic fibers, and glycoproteins) as an extracellular matrix. The extracellular matrix can be defined in part as any material part of a tissue that is not part of any cell. So defined, the extracellular matrix (ECM) can be the significant feature of the fibrous connective tissue.
The ECM's main component can be various glycoproteins. In most animals, the most abundant glycoprotein in the ECM can be collagen. Collagen can be tough and flexible and gives strength to the connective tissue. Indeed, the main element of the fibrous connective tissue is collagen (or collagenous) fiber. The ECM also contains many other components: proteins such as fibrin and elastin, minerals such as hydroxyapatite, or fluids such as blood plasma or serum with secreted free flowing antigens. Given this diversity, it can serve any number of functions, such as providing support and anchorage for cells (which attach via focal adhesions), providing a way of separating the tissues, and regulating intercellular communication. Therefore, the ECM can function in a cell's dynamic behavior.
Injury to tendons and ligaments causes damage not only to the connective tissue, but to the extracellular matrix as well. Damage to the ECM can interrupt cell behavior in the connective tissue and decrease and/or limit healing. After injury, continuing damage can be caused by production of matrix metalloproteinases (MMPs) by the body. MMPs are enzymes that degrade all components of the ECM. This can lead to an imbalance between the synthesis and degradation of the ECM, as the body tries to heal itself while the enzymes remodel the ECM. An overabundance of remodeling by MMPs cause damage to previously connected tissue which results in the formation of scar tissue. In addition, scar tissue adhesion to surrounding tissue can cause further pulling and/or stretching of the tendons or ligaments and resultant pain.
Currently, treatment of injury to tendons and ligaments includes some simple measures such as: avoiding activities that aggravate the problem; resting the injured area; icing the area the day of the injury; and taking over-the-counter anti-inflammatory medicines. However, these simple remedies do not always cure the injury and often more advanced treatments are needed. These treatments include: corticosteroid injections, platelet-rich plasma (PRP), hyaluronic acid (HA) injection, physical therapy and even surgery. Corticosteroids are often used because they can work quickly to decrease the inflammation and pain. Physical therapy can include range of motion exercises and splinting (such as for the fingers, hands, and forearm). Surgery can be only rarely needed for severe problems not responding to the other treatments. It can be appreciated that additional treatment measures are needed to treat and prevent extracellular matrix degradation for quicker and improved healing of tendons and ligaments.
Alpha-2-macroglobulin (A2M) is a highly conserved protease inhibitor present in plasma at relatively high concentrations (0.1-6 mg/ml). It is unique in its ability to inhibit all the major classes of proteases (Bhattacharjee et al (2000) J. Biol. Chem. 275, 26806-26811). A2M can be produced by several cell types, such as hepatocytes, lung fibroblasts, macrophages, astrocytes and tumor cells (Borth W, “Alpha 2-macroglobulin, A multifunctional binding and targeting protein with possible roles in immunity and autoimmunity,” Ann. N.Y. Acad. Sci. 737:267-272 (1994)). A2M often exists as a tetramer of four identical 180 kDa subunits that forms a hollow cylinder-like structure. It can present multiple target peptide bonds to attacking proteases in its central “bait” domain. A2M can be the major protease inhibitor acting on foreign proteases, such as snake venoms. However, there are many other protease inhibitors in the circulation and it has been proposed that A2M can have other functions including binding to and regulation of cytokine and growth factor activity, promotion of tumoricidal capabilities of macrophages, and enhancement of antigen presentation. A2M can also be a targeting carrier for cytokines or growth factors.